Double Strength Supports Cardiovascular Function Promotes Relaxation L-Theanine is an amino acid naturally found in green tea. L-Theanine promotes relaxation without the drowsiness or negative side effects associated with other calming agents. L-Theanine also supports healthy cardiovascular function through this relaxing effect. This formulation also includes Inositol, a member of the B-Vitamin family that is essential for brain and nervous system health.